IRVING, Texas (AP) — Tony Romo missed practice again Monday. It was hard to tell whether it was rest for his surgically repaired back or the first of a few days off, assuming the Dallas quarterback is finished for the preseason.

If Romo has taken his final exhibition snap, he and the Cowboys don't have much to build on for the Sept. 7 opener against San Francisco. He led two ragged quarters in a 25-20 loss to Miami and isn't likely to play against Denver on Thursday night.

Here's all anyone needs to know about how the Dallas offense played in Romo's second game since surgery for a herniated disk last December. The Cowboys were pleased to see his back hold up through three sacks and another knockdown.

"The negative plays, the sacks, certainly were an issue for our offense," coach Jason Garrett said. "Some holding penalties, some stuff that got us behind the chains, kept us out of rhythm. When you kind of pull back, you say, 'OK, there were some good things here.' There were some good individual performances."

The highlight for the first-team offense was a fourth-down conversion from Romo to Dez Bryant to set up the first Dallas field goal. The Cowboys were in position to go to halftime feeling a little better about things, but a penalty and a sack forced them to settle for another field goal.

Now Romo figures to be watching the backups and the battles for final roster spots against the Broncos after getting 34 snaps in Miami. He had 41 snaps in his most extensive preseason action last year, when he was four months removed from surgery to remove a cyst from his back.

"I think each year is a little different," said Romo, who was 10 of 18 for 84 yards. "If we would have probably scored in the first drive or two we might have been done at 28 or 30. It was good to kind of play a half and just kind of get in that mode and kind of work out some of the road communication things that came up."

One drive against Miami ended when Romo threw behind Cole Beasley and the sure-handed receiver couldn't hang on. A young offensive line that's drawn praise throughout training camp led to most of the other glitches.

Two of the sacks on Romo included penalties on offensive linemen that were declined, and a holding call on Pro Bowler Tyron Smith doomed another possession.

"It's a matter of inches," center Travis Frederick said. "And the things that we were off on, it wasn't as if this guy missed his block and that's why the play didn't work. It's really the tiny stuff and it's things that easily are correctable and things we've already worked on in practice."

After the Miami game, owner Jerry Jones suggested the offensive line might need more work against the Broncos. If the group that includes three first-round picks in the past four years doesn't play, the question becomes whether the linemen are ready.

"Yeah, everybody needs the work," Garrett said. "We talked about that after the game. If at any point you think like, 'OK, we're ready,' we're not ready. We're never going to be ready. You're always trying to get more ready. That's the approach we take."

And because Romo's preseason is likely finished, the bigger question is whether he's ready.

"This is the same kind of schedule that we've done in the preseason, so it doesn't feel all that different than any other year," the 34-year-old Romo said. "I think with obviously with coming off of surgery you're going to always talk about that, but that's part of the game."

NOTES: FB J.C. Copeland and DE Martez Wilson were waived a day before the roster has to be trimmed to 75 players. ... DT Henry Melton (groin) and CB Morris Claiborne (shoulder) did some work in a limited practice, but it remains unclear whether they will get their first preseason action against Denver. ... DT Terrell McClain (ankle) said he doesn't expect to play against the Broncos but hopes to ready for the opener against the 49ers.